A module for detecting and measuring current flowing in a conductor of a low-voltage distribution board is disclosed in DE 10 2006 059384 A1. This module has a box-like module housing in which a current sensor and a microprocessor circuit are arranged. A recess which can be used to releasably connect the module to the low-voltage distribution board is provided on the module housing. The housing has two openings through which one of two sections of a current conductor is respectively guided. Inside the housing, the two current conductor sections are respectively galvanically connected to current-carrying parts of the module via one of two current connections. On the one hand, this makes it difficult to mount the module. On the other hand, the module additionally requires space on a mounting rail or a plug-in socket of the low-voltage distribution board.
Another current measuring and current detection module is disclosed in DE 195 23 725 C2. This module is part of a low-voltage circuit-breaker which also has a three-pole switching contact arrangement with a switching mechanism. This module contains a housing with an opening through which a phase conductor of the low-voltage distribution board is guided, and the phase conductor is controlled by the switch. A current sensor, an auxiliary energy converter, and a printed circuit board with a microprocessor circuit are arranged in the housing. The microprocessor circuit processes signals emitted by the current sensor and transfers the signals to an interface for the purpose of feeding them into a bus system. The temperature and the voltage of the current conductor are also determined inside the module and are transferred to the interface. Data transferred to the interface are used, on the one hand, to control the switch and, on the other hand, for forwarding to a bus system with a central control room in which the detected values of the current carried in the current conductor or of other characteristic variables, such as voltage, temperature or power, and the corresponding data for further switches of the low-voltage distribution board can be displayed.
A current measuring module is also disclosed in DE 10 2007 006 219 A1. This module has a magnetic module for generating a potential-free output signal, which is proportional to the current to be detected, as well as an electronic module with an integrated circuit for detecting and processing the output signal from the magnetic module. In this case, the magnetic module includes a ferromagnetic toroidal core with or without an air gap. A primary conductor carrying the current is guided through the toroidal core. The toroidal core may be provided with a current-fed compensation winding or a current-supplying sensor winding. Additionally or alternatively, magnetic field probes can be used. The magnetic field probes act as current sensors and are in the form of a Hall probe or an inductive magnetic field probe. The magnetic field probes measure the strength of the magnetic flux in the air gap of the toroidal core or on the toroidal core, which magnetic flux is induced in the toroidal core by the magnetic field of the current flowing in the primary conductor.
The Smissline technical catalog “Innovativ installieren SCHUTZGERÄTE MIT STECKTECHNIK” [Innovative installation PLUG-IN PROTECTION DEVICES] by ABB Schweiz AG, Normelec, Badenerstr. 790, CH-8048 Zurich/Switzerland, describes a low-voltage distribution board in which switching and protective devices, which are each in the form of a modular DIN rail-mounted device, such as miniature circuit-breakers, residual current circuit-breakers and overvoltage and overcurrent protective devices, for example, are installed on plug-in sockets. In such low-voltage distribution boards, the current supplied from a low-voltage power supply system is distributed among different loads with the aid of the built-in devices which can be quickly installed, replaced or supplemented. Since the switches are in the form of circuit-breakers, the current-carrying loads are quickly and reliably protected from the consequences of overload and short-circuit currents. Switching and protective devices in the form of residual current circuit-breakers are even able to respond to very small residual currents in fractions of a second. Residual current circuit-breakers therefore interrupt the residual current even before risks to people and items can occur. In order to solve particular distribution problems, it may be necessary to know the magnitude of the current carried by a switching and protective device as a function of the time.